A study out this week in the New England Journal of Medicine suggests that people who have blood glucose levels that are elevated but not yet quite diabetic should consider taking a drug usually reserved for those with full-blown diabetes. We disagree.

The study found that after about two years of follow up, people who took pioglitazone (Actos) had a 72 percent reduction in their blood glucose measurements compared with those who took a placebo. In addition, for every 100 people who took the drug only about two developed diabetes, compared with about eight out of 100 who took the placebo. Finally, Actos lowered blood pressure and raised HDL (good) cholesterol.

So what's the problem? The drug caused weight gain (an average of about 8 pounds) as well as edema, a condition in which the body accumulates fluid in the legs. Even more worrisome, other research suggests that about three out of every 100 people who take Actos develop heart failure as a result. So the drug might be about as likely to cause heart failure as it is to prevent diabetes. In fact, the heart-failure risk is so great that Actos, as well as related drugs such as Avandia (rosiglitazone), have a black-box warning from the Food and Drug Administration about the risk, the strongest such warning available.

Moreover, an earlier analysis of multiple other studies suggests that lifestyle changes such as losing excess weight, staying active, and consuming a heart-healthy diet can also help prevent diabetes. In that analysis, about five out of 100 people who made lifestyle changes developed diabetes compared with about 11 out of 100 who had no treatment. While that's not quite as impressive as Actos was in the current study, lifestyle changes have other benefits especially important to people with high blood sugar levels--such as losing weight and lowering blood pressure and LDL (bad) cholesterol levels--all without any of the risks of Actos.

Bottom line: Prediabetes is a serious condition affecting up to 79 million Americans and should be addressed. While Actos might be better than nothing, our medical consultants say given the known risks of the drug, lifestyle changes remain by far the best way to treat it and prevent diabetes.

In addition, when a study is entirely funded by a drug's manufacturer and some of its researchers have received payments from the company, as is the case with this Actos study, it pays for consumers to dig deeper into the findings.

See our Best Buy Drugs report on drugs for type 2 diabetes.

Pioglitazone for Diabetes Prevention in Impaired Glucose Tolerance [New England Journal of Medicine]